JP2018004918A5 - - Google Patents

Description

In order to achieve the above object, the focus adjustment apparatus of the present invention is configured to detect a region of a subject to be tracked from the image signal output from an imaging unit that photoelectrically converts incident light and output an image signal, and the region of the region. Tracking means for detecting the image plane position and reliability, prediction means for predicting the image plane position at a predetermined time based on the history of the image plane position detected by the tracking means, and detection by the tracking means A setting means for setting an error range of the image plane position based on the reliability, an image plane position at the time of photographing of the image signal predicted by the prediction means, and an image detected by the tracking means. the difference between the surface position is, the when in the error range, and determining means for determining the area of the object detected by the tracking means as focus control area, Four to focus on the focus control area A calculating means for calculating a driving amount of Surenzu, wherein the prediction means further predicts the image plane position of an object included in the focusing area in the predetermined time in the future, the calculating means Calculates the drive amount so as to focus on the image plane position at the predicted future time point.

FIG. 2 is a cross-sectional view of an imaging apparatus according to an embodiment of the present invention, and a block diagram illustrating a functional configuration of the imaging apparatus. The figure which shows the structure of the image pick-up element in embodiment. Schematic explanatory drawing of the pixel structure and pupil division in the embodiment. 6 is a flowchart of focus adjustment and imaging processing in the embodiment. 6 is a flowchart of subject tracking processing in the embodiment. The figure which shows the example of the template matching in embodiment. The flowchart of the focus detection process in embodiment. 10 is a flowchart of focus adjustment region setting processing in the embodiment. The figure explaining the threshold value setting of the image surface direction in embodiment. The flowchart of the imaging | photography prediction process in embodiment.

In the present embodiment, an interchangeable lens digital still camera that uses a combination of a camera body 100 having a finder 104 and an image sensor 103 and a photographing lens 120 having a photographing optical system will be described as an imaging device. However, the present invention is not limited to a digital still camera with interchangeable lenses, it may be applied to various optical apparatus capable of performing focus adjustment on the basis of the image signal.

The display 105 is formed by an LCD (Liquid Crystal Display) panel or the like, and displays a captured image and information such as shooting information. In addition, the display device 105 displays a moving image in real time in the live view mode. Here, the live view mode refers to a subject image that is incident through the photographing lens 120 and is formed on the image sensor 103 as a moving image having a low pixel number for previewing, and is displayed on the display 105 in real time. Mode. In the live view mode, phase difference AF on the imaging surface described later can be executed. Furthermore, during continuous shooting, a still image with a low pixel count at each continuous shooting is displayed on the display 105.

The focus adjustment unit 114 instructs the lens CPU 122 to move the focus position based on the converted defocus amount. Further, the focus adjustment unit 114 predicts a future image plane position using the prediction unit 119, calculates a lens driving amount necessary for the focal position of the photographing lens 120 to reach the predicted image plane position, and sends it to the lens CPU 122. Give instructions.

Next, the tracking process when it is determined in S202 that there is a subject to be tracked will be described. In this case, it is performing Oite matching process in S205. Here, the details of template matching will be described with reference to FIG. FIG. 6A shows an example of a subject model (template) in template matching. Reference numeral 601 denotes a partial image (template) indicating the subject to be tracked, and the pixel pattern of this image is handled as a feature amount. Reference numeral 602 represents a feature amount of the template 601 and a luminance signal of pixel data is used as the feature amount. The feature amount T (i, j) is expressed by Expression (1) where the coordinates in the template region are (i, j), the number of horizontal pixels is W, and the number of vertical pixels is H.
T (i, j) = {T (0, 0), T (1, 0), ..., T (W-1, H-1)} (1)

Next, in S405, it is determined whether the image plane position of the tracking area calculated in S101 is within the error range set in S403 or S404. If it is within the error range (YES in S405), the tracking area is set as the focus adjustment area in S406. On the other hand, if the image plane position of the tracking region has not fall within the error range (NO at S405), at S407, in the region of obtaining the defocus amount at S10 2, the image surface position based on the prediction equation obtained in S401 An area close to the defocus amount is set as the focus adjustment area. If there is no region close to the defocus amount of the image plane position based on the prediction formula, focus adjustment is not performed.

Subsequently, the focus adjustment area setting unit 115 corresponds to the image plane position calculated in S506 or the defocus amount calculated in S507 with respect to the image plane position of the focus adjustment area set in S406 or S407 in FIG. The difference in image plane position is determined. Here, the relationship between the image plane position difference and the error range T1 set in S404 is determined in S508. If the image plane position is within the error range T1 (NO in S508), no additional processing is performed and the processing ends. On the other hand, if the image plane position is equal to or larger than the error range T1 (YES in S508), a part of the history data of the image plane position used in the next prediction unit 119 is reset in S509. Here, for example, a certain number or a certain proportion of data is deleted from the oldest one. By reducing the influence of past image plane position information, the prediction accuracy for a tracking subject irregular in the optical axis direction is improved.

Claims (14)

A tracking means for detecting a region of a subject to be tracked, an image plane position and reliability of the region, from the image signal output from an imaging unit that photoelectrically converts incident light and outputs an image signal;
Prediction means for predicting the image plane position at a predetermined time point based on the history of the image plane position detected by the tracking means;
Setting means for setting an error range of the image plane position based on the reliability detected by the tracking means;
When the difference between the image plane position at the time of photographing of the image signal predicted by the prediction unit and the image plane position detected by the tracking unit is within the error range, the difference is detected by the tracking unit. Determining means for determining the subject area as a focus adjustment area;
Calculating means for calculating a driving amount of a focus lens for focusing on the focus adjustment region;
The predicting means further predicts an image plane position of a subject included in the focus adjustment area at a predetermined future time point, and the calculating means calculates the image plane position at the predicted future time point. A focus adjustment device that calculates the drive amount so as to focus.   The setting means sets a first error range when the reliability is equal to or lower than a predetermined threshold value, and sets the first error range when the reliability is higher than a predetermined threshold value. The focus adjustment apparatus according to claim 1, wherein a second error range that is too wide is set.   The focus adjustment apparatus according to claim 1, wherein the setting unit expands the error range stepwise as the reliability increases.   The focus adjustment apparatus according to claim 1, wherein the setting unit widens the error range as the reliability increases. If the difference between the image plane position at the time of photographing and the predicted image plane position of the subject at a future time point is not within the error range, at least a part of the history of the image plane position is old. The focus adjustment apparatus according to claim 1, wherein the focus adjustment apparatus is deleted from the direction. When the difference between the image plane position at the photographing time predicted by the prediction unit and the image plane position detected by the tracking unit is not within the error range, the determination unit 6. The focus according to claim 1, wherein an area of the image signal having an image plane position close to the predicted image plane position at the time of photographing is determined as the focus adjustment area. Adjusting device. Wherein when a region of the image signal having an image plane position closer to the image plane position at the predicted the photographing time by the prediction means is absent, the calculating means, claims, characterized in that not calculate the driving amount 6. The focus adjustment device according to 6.   The tracking means uses the region of the subject to be tracked as a template to collate with a partial region of the image signal to obtain an evaluation value, and obtains the reliability according to the distribution of the evaluation value. Item 8. The focus adjustment device according to any one of Items 1 to 7. The tracking means detects a region of the subject based on a distribution of characteristic colors of the subject in the image signal, and obtains the reliability based on a distribution of characteristic colors inside and outside the region. The focus adjustment apparatus according to claim 1, wherein the focus adjustment apparatus is characterized in that:   10. The focus adjustment according to claim 1, wherein the tracking unit obtains the reliability of the image signal with reference to the reliability history when the reliability is obtained. apparatus. Imaging means for photoelectrically converting incident light and outputting an image signal;
An imaging apparatus comprising: the focus adjustment apparatus according to claim 1. A tracking step in which tracking means detects the area of the subject to be tracked, the image plane position and reliability of the area from the image signal output from the imaging means that photoelectrically converts incident light and outputs an image signal; ,
A predicting step for predicting an image plane position at the time of capturing the image signal based on a history of the image plane position detected in the tracking step;
A setting step for setting an error range of the image plane position based on the reliability detected in the tracking step;
When the difference between the image plane position at the time of shooting of the image signal predicted in the prediction step and the image plane position detected in the tracking step is within the error range, A determination step of determining the subject area detected in the step as a focus adjustment region;
A second prediction step in which the prediction means further predicts an image plane position of a subject included in the focus adjustment area at a predetermined future time point;
And a calculating step of calculating a driving amount of a focus lens for focusing on the image plane position predicted in the second prediction step.   The program for functioning a computer as each means of the focus adjustment apparatus of any one of Claims 1 thru | or 10.   A computer-readable storage medium storing the program according to claim 13.

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